Rocket & Onion Frittata

We're already dreaming of the picnics we'll have this summer: cold chicken sandwiches (bereft of crusts, naturally!), hand-raised pork pies, heavenly Brie de Meaux & and our splendid frittata, with sweet onions and herby rocket

You'll need to start by reducing the onions to a sweet, sticky confit. Melt a good knob of butter in a thick-based frying pan and add the thinly sliced onions. Cook on a low heat, stirring from time to time, for about 25 mins, till the onions are caramelised and tender. Season and beat the eggs, adding to the onions. Keep the heat moderate for a further 15 mins or so. The eggs will begin to set and the bottom will turn golden. Add a good handful of rocket and allow to wilt before sprinkling on the Gruyere. Take off the heat and brown for a few minutes under a hot grill. Serve with salad